H9N2 avian influenza explained: Causes, symptoms and precautions amid recent outbreaks in China

Avian influenza, commonly referred to as bird flu, is a viral infection that predominantly impacts birds. One noteworthy subtype, H9N2, has garnered attention due to its capacity to infect diverse bird species and sporadically transmit to humans. Recent clusters of respiratory illness in children in northern China have heightened concern about H9N2, making it crucial to understand its causes, symptoms, and preventive measures.

Causes

H9N2 belongs to the Influenza A virus subtype within the Orthomyxoviridae family. Its primary targets are birds, particularly prevalent in poultry like chickens and turkeys. The virus can undergo genetic reassortment, resulting in the emergence of novel strains. Transmission occurs through direct contact with infected birds, their respiratory secretions, or contaminated environments. Persistence in water and on surfaces contributes to its spread, with a human case reported in China in October 2023.

Symptoms

In poultry, H9N2 infections vary from asymptomatic to severe, influenced by factors such as bird species, age, and coexistence with other pathogens. Common bird symptoms encompass respiratory distress, reduced egg production, and decreased feed consumption. Human symptoms mirror those of other influenza viruses, including fever, cough, sore throat, and breathing difficulties.

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Preventive measures

Implementing stringent biosecurity measures is crucial to forestall H9N2 introduction and spread in poultry farms. This involves regulating farm access, regular facility disinfection, and ensuring contamination-free personnel and equipment. Vigilant poultry population surveillance aids early H9N2 detection. Maintaining bird health through routine testing and prompt reporting of unusual illnesses is pivotal in preventing virus dissemination.

Hygiene practices

Rigorous hygiene practices are imperative in both commercial and backyard poultry settings. Proper waste disposal, routine cleaning and disinfection of equipment and facilities, and the use of protective clothing by farm workers are essential. Educating poultry stakeholders and the public about H9N2 risks is vital. Awareness campaigns can disseminate information on hygiene practices, the significance of early detection, and potential consequences. Those in contact with infected birds should regularly clean hands and disinfect clothes and belongings to minimize the risk of human transmission.

India's preparedness

India's Union Health Ministry is closely monitoring the reported H9N2 cases and respiratory illness clusters in northern China. "Union Health Ministry is closely monitoring the reported outbreak of H9N2 cases and clusters of respiratory illness in children in northern China. There is low risk to India from both the avian influenza case reported from China as well as the clusters of respiratory illness," as per an official statement made on November 24.

The World Health Organization's overall risk assessment indicates a low probability of human-to-human spread and a low case fatality rate among reported H9N2 human cases.

• Explainer
• China
• H9N2
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